High cholesterol is one of a number of risk factors for heart attack and stroke. Although poor diet and lack of excise are common causes of high cholesterol, genetic changes, such as familiar hypercholesterolemia (FH), which is caused by deficiency in LDLR, can be causes of high cholesterol. A number of cholesterol lowering drugs are currently on the market but they are not without risk or contraindications with certain conditions or other medications. Such drugs include statins, fibrates, niacin, bile acid sequestrants (resins), phytosterols, or other compounds that prevent absorption of fats, reduce absorption of cholesterol, or target genes in the cholesterol trafficking pathway.
Nucleic acid based cholesterol lowering drugs include, for example an antisense oligonucleotide inhibitor which targets ApoB-100, mipomersen, which was approved in January 2013 for the treatment of homozygous familial hypercholesterolemia (FH). In December of 2012, the FDA also approved lomitapide for the same condition.
More troubling are the liver related problems associated with cholesterol targeting drugs, particularly elevation in serum transaminases and accumulation of hepatic fat (or hepatic steatosis). For example, because of the potentially significant safety concerns surrounding mipomersen, the drug will carry a boxed warning about liver toxicity as well as requiring certification of prescribers and pharmacies, as well as documentation that the drug is being properly used with each new prescription. While mipomersen was generally effective in lowering LDL cholesterol (more than half of patients in clinical trials had more than a 20% decrease in LDL levels and in the homozygous FH trial, it reduced LDL by 24.7%), a typical FH patient has an average LDL between 400-1000 mg/dL. Consequently, lowering was not likely enough in these patients. In addition, the trials were not large enough to be powered to assess cardiovascular outcomes, though cardiovascular benefit is of course the ultimate intended effect of the drug. Further, serious adverse events of cardiac disorders occurred in the mipomersen group in phase 3 trials.
The present invention addresses the problem of the degradation of LDLR by providing polynucleotides which encode a polypeptide of interest comprising at least one mutation, e.g., a LDLR cell surface expression-enhancing mutation, a mutation increasing the residence time of LDLR at the cell surface or a mutation resulting in increased levels of LDLR at the cell surface. The present invention addresses this need by providing nucleic acid based compounds or polynucleotides (both coding and non-coding and combinations thereof) which have structural and/or chemical features that avoid one or more of the problems in the art, for example, features which are useful for optimizing nucleic acid-based therapeutics while retaining structural and functional integrity, overcoming the threshold of expression, improving expression rates, half life and/or protein concentrations, optimizing protein localization, and avoiding deleterious bio-responses such as the immune response and/or degradation pathways. These barriers may be reduced or eliminated using the present invention.